Probable Purple Heron over school!

During break (10am) at Ysgol Dyffryn Taf, Whitland, I watched what appeared to be a first summer Purple Heron flying over the trees alongside the school field. It looked similar to Grey Heron but it had black/dark wings with brown wing-coverts, long trailing legs, long toes and looked, all in all, slightly smaller than a Grey Heron. Unfortunately, I could not see the head, as it was flying away from me. After flying over the school field, it headed north west. I am not 100% certain, but I am pretty sure what I saw was a Purple Heron!